CHICAGO RADIO TUBE AMPLIFIER

[srini1785]

Hello,

I'm trying to restore a vintage Chicago Radio Tube amplifier (mostly used as a PA system). Presently, it has on its chassis a ECC83 pre amp and NEC valve (details not visible) in the amplifier stages. The amp is mostly intact except someone has changed the power stage from tube to diode (IN4007). I did send a message to Motwani communications (Present name of Chicago Radio) but no reply from them. What I need is more info on this amp and if possible any schematic. I want to restore it back to original specs.

Thanks

 

[Hiten]

I would recommend to check power and audio output transformer to see if they are working or not. Good transformers will increase your budget significantly in restoration.
regds.

 

[Hiten]

Addition : Also if this is PA amplifier system. there are good chances of its audio output transformer will be band limited. So dont go for specifications just see if it can be restored as a working amplifier.

 

[yogibear]

Iron seems to be completely rusted so no point working on it. 5881 tubes ?Chicago iron is well regarded and particularly for Push Pull circuits.

I restored and fired mine recently, a mono 6L6 PP amplifier which doesn't sound an iota like a PP but SE. It's a Heathkit W4 AM based on all Chicago iron. Excellent sound.

 

[srini1785]

Yes, I'll test it shortly with a pilot bulb. The rust seems to be only on the surface. I'm working on another tube amp and will update this thread shortly. So, I guess there is no point trying to get schematics?

 

[yogibear]

If iron is fine, and no issues under load, I would rather build an amp around them. Strip and use the same chassis. 6L6 PP would be excellent choice.